Is it possible to link datas from a REST connector using anything other than __KEY_root?

[Saijoken]

I am trying to link datas in a single JSON REST connector one part is from a simple call to the "root" part of the JSON :

NoConcatenate
    RestConnectorMasterTable:
    SQL SELECT
        "id" AS "newid",
        "created_at",
        "updated_at",
        "status",
        "source",
        "product_id",
        "__KEY_root"
    FROM JSON (wrap on) "root" PK "__KEY_root"
    WITH CONNECTION (
        URL "https://api.com/api/v2/tickets?per_page=100&page=1&updated_since=2024-10-29T15:50:00Z&order_by=updated_at&order_type=asc"
    );

 The other part is from some "subdatas" in the JSON that I need to get separately :

NoConcatenate
    CustomFields:
    SQL SELECT
    (SELECT 
      "domain",
      "site",
      "category"
      FROM "custom_fields" FK "__FK_custom_fields")
    FROM JSON (wrap on) "root" PK "__KEY_root"
    WITH CONNECTION (
        URL "https://api.com/api/v2/tickets?per_page=100&page=1&updated_since=2024-10-29T15:50:00Z&order_by=updated_at&order_type=asc"
    );

 It works like that when I link __FK_custom_fields to __KEY_root since values are added by the REST connector in Qlik but I want to link it through the ticket ID so that I can make sure my datas are linked correctly in any case scenario.